Outer coating substrate for electronic component and piezoelectric resonant component

ABSTRACT

An outer coating substrate for an electronic component is constructed to be calcined at a low temperature, and greatly decreases the cost thereof while greatly improving the dimensional precision of the substrate. The outer coating substrate for an electronic component includes a multi-layered substrate including a first material layer that is sintered in a liquid phase and a second material layer that is not sintered at the sintering temperature of the first material layer. The first and second material layers are laminated, and calcined at the calcining temperature of the first material layer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to outer coating substrates forelectronic components, for example, piezoelectric oscillators, andpiezoelectric resonant components including the outer coatingsubstrates. In particular, the present invention relates to outercoating substrates for electronic components which are constituted bylaminating various material layers, and piezoelectric resonantcomponents using the outer coating substrates.

[0003] 2. Description of the Related Art

[0004] In electronic components, for example, piezoelectric oscillators,outer coating substrates made of ceramics have been widely used toprotect electronic component elements.

[0005] For example, a piezoelectric resonator 101 shown in FIG. 10 isdisclosed in Japanese Unexamined Patent Application PublicationNo.4-4604. In the piezoelectric resonator 101, outer coating substrates103 and 104 are laminated on the top and bottom of an energy trappiezoelectric resonant element 102. The outer coating substrates 103 and104 are made of alumina obtained by low temperature calcining. Ceramics,for example, alumina, is superior in strength. However, manufacturingcosts are high due to high calcining temperatures. It is disclosed inJapanese Unexamined Patent Application Publication No.44604 that thecalcining temperatures are lowered to reduce the manufacturing costs.

[0006] On the other hand, a crystal oscillator shown in FIG. 11 isdisclosed in Japanese Unexamined Patent Application PublicationNo.9-208261. In this disclosure, the crystal oscillator 112 is sealed ina package composed of a base member 113 and a cap member 114. The basemember 113 and the cap member 114 are made of a glass-ceramics compositeso that calcining at a low temperature of about 800° C. to 1000° C. isdescribed as being possible.

[0007] Furthermore, a composite layer ceramic component shown in FIG. 12is disclosed in Japanese Unexamined Patent Application Publication No.10-106880. In this disclosure, low dielectric constant layers 121 and124 are arranged as outermost layers, and the low dielectric constantlayers 121 and 124 are made of a mixed material of ceramic powder andamorphous glass. High dielectric constant layers 122 and 123 arearranged between the low dielectric constant layers 121 and 124. It isdescribed that characteristics of capacitors, resonators, and otherelectronic components, which include conductor layers 125 and 126, areimproved by the high dielectric constant layers 122 and 123.

[0008] The outer coating substrates 103 and 104 of the piezoelectricresonator described in Japanese Unexamined Patent ApplicationPublication No.4-4604 can be calcined at a relatively low temperature.However, the contraction rate during calcination is large. Therefore, ithas been a problem that the dimensional precision of the outer coatingsubstrates 103 and 104 is insufficient.

[0009] On the other hand, a glass-ceramics composite is used in thestructure described in Japanese Unexamined Patent ApplicationPublication No.9-208261 and in Japanese Unexamined Patent ApplicationPublication No.10-106880. The glass-ceramics composite can be calcinedat a low temperature. However, the contraction rate during calcinationis large also, and the precision of substrate dimension has beeninsufficient.

SUMMARY OF THE INVENTION

[0010] In order to overcome the problems described above, preferredembodiments of the present invention provide an outer coating substratefor an electronic component that is arranged to be calcined at a lowtemperature, and to achieve greatly improved dimensional precision. Inaddition, preferred embodiments of the present invention provide apiezoelectric resonant component having an outer coating substrate thatis arranged to be calcined at a low temperature and is superior indimensional precision, while also being low cost.

[0011] According to a first preferred embodiment of the presentinvention, an outer coating substrate for an electronic componentincludes a multi-layered substrate having a first material layer and asecond material layer laminated together, wherein the first materiallayer is sintered in a liquid phase and the second material layer is notsintered at the sintering temperature of the first material layer.

[0012] In one preferred embodiment of the present invention, the firstmaterial layer is preferably made of glass or glass-ceramics.

[0013] It is also preferable that the first material layer does notcontain a component that dissolves into a wet plating bath.

[0014] Also, a concave portion is preferably formed on at least onemajor surface of the substrate.

[0015] The outer coating substrate preferably has at least one pair ofcapacitive electrodes, arranged to interpose at least a portion of thesecond material layer, and a capacitor is defined by the pair ofcapacitive electrodes.

[0016] In other preferred embodiment of the present invention, aresistive element and an inductance element are preferably provided inthe outer coating substrate and are made of a resistive material and amagnetic material.

[0017] In another preferred embodiment of the present invention, atleast two layers of the first material layer are laminated with thesecond material layer in the substrate.

[0018] According to another preferred embodiment of the presentinvention, a piezoelectric resonant component includes a piezoelectricresonant element and first and second outer coating substrates laminatedon the top and bottom of the piezoelectric resonant element, wherein atleast one of the first and second outer coating substrates includes amulti-layered substrate having a laminate structure having a firstmaterial layer that is sintered in a liquid phase and a second materiallayer that is not sintered at the sintering temperature of the firstmaterial layer.

[0019] In one specific example of the preferred embodiment described inthe preceding paragraph, the piezoelectric resonant element is an energytrap piezoelectric resonant element, and the first and second outercoating substrates are laminated on the piezoelectric resonant elementso as to define a space that allows for free and unhindered vibration ofresonant portion of the energy trap piezoelectric resonant element.

[0020] In another preferred embodiment of the present invention, aconcave portion is preferably provided on a surface of at least one ofthe first and second outer coating substrates, so as to define a spacethat allows for free and unhindered vibration of resonant portion of theenergy trap piezoelectric resonant element.

[0021] It is preferred that the first material layer is made of glass orglass-ceramics in this preferred embodiment of the present invention.

[0022] It is also preferred that the first and second outer coatingsubstrates do not contain a component that dissolves into a wet platingbath.

[0023] In at least one of the first and second outer coating substrates,at least one pair of capacitive electrodes is arranged to interpose atleast a portion of the first material layer, and a capacitor is definedby the pair of capacitive electrodes.

[0024] Also, in at least one of the first and second outer coatingsubstrates, a resistive element and an inductance element are preferablyprovided and include a resistive material and a magnetic material,respectively.

[0025] In addition, at least one of the first and second outer coatingsubstrates preferably has a plurality of the first material layers.

[0026] According to various preferred embodiments of the presentinvention, a piezoelectric resonant component includes a packagesubstrate, a piezoelectric resonant element fixed on the packagesubstrate, and a junction member fixing the piezoelectric resonantelement to the package substrate, wherein the Young's modulus of thepackage substrate is less than a Young's modulus of a piezoelectricmaterial constituting the piezoelectric resonant element.

[0027] In such a preferred embodiment of the present invention, thepackage substrate is preferably a multilayered package substrate havingat least two layers.

[0028] The multi-layered package substrate preferably includes a firstlayer having a Young's modulus that is greater than the Young's modulusof the piezoelectric material, and a second layer having a Young'smodulus that is less than the Young's modulus of the piezoelectricmaterial.

[0029] The second layer having the smaller Young's modulus is preferablymade of a composite material of amorphous glass and ceramic powder, andthe second layer having the greater Young's modulus is preferably madeof Al₂O₃ or MgTiO_(3.)

[0030] The piezoelectric resonant element is preferably an energy trappiezoelectric resonant element having a piezoelectric plate, and aresonant portion partially provided on the piezoelectric plate.

[0031] Piezoelectric resonant components according to various preferredembodiments of the present invention are possible to be formed ascomponents having various structures according to the aforementionedpiezoelectric resonant element, the package substrate, and the junctionmember.

[0032] In a preferred embodiment of the present invention, packagesubstrates are preferably laminated on both sides of the piezoelectricresonant element so as to allow for free and unhindered vibration of thepiezoelectric resonant element.

[0033] Furthermore, a cap is preferably joined to the package substratein order to surround the piezoelectric resonant element fixed on thepackage substrate.

[0034] The package substrate preferably has a concave portion toaccommodate the piezoelectric resonant element, and, furthermore, acover member is preferably fixed to the package substrate to close theconcave portion.

[0035] Other features, characteristics, elements and advantages of thepresent invention will become more apparent from the detaileddescription of preferred embodiments thereof with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWING

[0036]FIGS. 1A and 1B are a perspective assembly view of a piezoelectricresonant component and a perspective assembly view of one outer coatingsubstrate according to the first preferred embodiment of the presentinvention;

[0037]FIG. 2 is a perspective view of a piezoelectric resonant componentaccording to a preferred embodiment of the present invention;

[0038]FIGS. 3A to 3D are sectional views of modified examplesrepresenting various arrangements of the first and second materiallayers in an outer coating substrate according to various preferredembodiments of the present invention;

[0039]FIGS. 4A and 4B are a perspective assembly view of a piezoelectricresonant component and a perspective assembly view of one outer coatingsubstrate according to the second preferred embodiment of the presentinvention;

[0040]FIG. 5 is a perspective assembly view of a piezoelectric resonantcomponent according to the third preferred embodiment of the presentinvention;

[0041]FIG. 6 is a perspective assembly view of an outer coatingsubstrate used in the piezoelectric resonant component according to thethird preferred embodiment of the present invention;

[0042]FIG. 7 is a sectional view illustrating a modified example of anouter coating substrate according to various preferred embodiments ofthe present invention;

[0043]FIG. 8 is a sectional view illustrating a state of an outercoating substrate in which a warp has been generated;

[0044]FIG. 9 is a sectional view illustrating another modified exampleof an outer coating substrate according to various preferred embodimentsof the present invention;

[0045]FIG. 10 is a sectional view of an example of conventionalpiezoelectric resonators;

[0046]FIG. 11 is a sectional view of another example of conventionalpiezoelectric resonant components;

[0047]FIG. 12 is a sectional view of another example of conventionalelectronic components;

[0048]FIGS. 13A and 13B are a sectional view and a perspective externalappearance of a piezoelectric resonant component according to the fourthpreferred embodiment of the present invention;

[0049]FIG. 14 is a sectional view of a piezoelectric resonant componentaccording to the fifth preferred embodiment of the present invention;

[0050]FIG. 15 is a sectional view of a piezoelectric resonant componentaccording to the sixth preferred embodiment of the present invention;

[0051]FIG. 16 is a sectional view of a piezoelectric resonant componentaccording to the seventh preferred embodiment of the present invention;

[0052]FIG. 17 is a sectional view of a piezoelectric resonant componentaccording to the eighth preferred embodiment of the present invention;

[0053]FIG. 18 is a sectional view of a piezoelectric resonant componentaccording to the ninth preferred embodiment of the present invention;and

[0054]FIG. 19 is a sectional view of a piezoelectric resonant componentaccording to the tenth preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0055]FIG. 2 is a perspective view of a piezoelectric resonant componentaccording to the first preferred embodiment of the present invention. Apiezoelectric resonant component 1 preferably includes first and secondouter coating substrates 5 and 6 disposed on the top and bottom of apiezoelectric resonant element 2 interposing adhesive layers 3 and 4.

[0056] External electrodes 7 to 9 are provided on the outer surface ofthe piezoelectric resonant component 1. In the piezoelectric resonantcomponent 1, the outer electrodes 7 to 9 are arranged, respectively, toextend over a pair of side surfaces, a bottom surface, and a componentof the top surface of the outer surface of a laminate wherein theaforementioned piezoelectric resonant element 2, adhesive layers 3 and4, and outer coating substrates 5 and 6 are laminated. In other words,the outer electrodes 7 to 9 are arranged to wind around the periphery ofthe aforementioned laminate except for being cut off on the top surfaceof the laminate as shown in FIG. 2. A component of the outer electrodeextending on the top surface of the laminate may be omitted.

[0057] This preferred embodiment includes a unique arrangement of theouter coating substrates 5 and 6. The aforementioned piezoelectricresonant component is explained in detail with reference to FIGS. 1A and1B.

[0058]FIG. 1A is a perspective assembly view of a piezoelectric resonantcomponent 1, and FIG. 1B is a perspective assembly view of a lower outercoating substrate 4.

[0059] As shown in FIG. 1A, the piezoelectric resonant element 2preferably includes a piezoelectric plate 10 having a substantiallyrectangular shape. The piezoelectric plate 10 is preferably made of apiezoelectric ceramic material, for example, a lead zirconate titanateceramics, or a piezoelectric single crystal, for example, crystal.

[0060] An excitation electrode 11 is disposed at the approximate centerof the top surface of the piezoelectric plate 10. An excitationelectrode, not shown in FIG. 1, is also provided at the approximatecenter of bottom surface of the piezoelectric plate 10, and theexcitation electrode of the bottom surface and the excitation electrode11 are arranged to face each other on the top and bottom surfacesinterposing the piezoelectric plate 10.

[0061] On the top surface of the piezoelectric plate 10, the excitationelectrode 11 is connected to a leading electrode 12 arranged along anend edge 10 a. The leading electrode 12 is arranged to reach both sideedges of the piezoelectric plate 10. Hereafter, the side edge means theouter edge extending in a direction that is perpendicular to the endedge 10 a and corresponds ultimately to an exposed component on the sidesurface of the laminate. That is, in the piezoelectric resonantcomponent 1, the leading electrode 12 is exposed on a pair of sidesurfaces of the aforementioned laminate.

[0062] Then, the leading electrode 12 is electrically connected to theouter electrode 7 on the side surface of the laminate.

[0063] Similarly, the excitation electrode disposed on the bottomsurface is also connected to a leading electrode, and the leadingelectrode, arranged to reach both side edges on the bottom surface ofthe piezoelectric plate 10, is electrically connected to the outerelectrode 8.

[0064] The aforementioned piezoelectric resonant element 2 is preferablyan energy trap piezoelectric resonant element, and a resonant portionpreferably includes the component having the excitation electrode 11arranged to face the excitation electrode on the bottom surface. Theadhesive layers 3 and 4 have openings 3 a and 3 b, respectively, todefine a space that allows for free and unhindered vibration of theresonant portion, That is, the adhesive layers 3 and 4 have a planshaped, substantially rectangular frame.

[0065] As shown in FIG. 1B, the outer coating substrate 6 has astructure including a plurality of material layers 13 to 17 arelaminated interposing inner electrodes 18 to 20. The material layers 14and 16 are the first material layers which are preferably made of amaterial that is sintered in a liquid phase, and the material layers 13,15, and 17 are the second material layers that are not sintered at thesintering temperature of the first material layers 14 and 16.

[0066] That is, in this preferred embodiment, the first material layers14 and 16 and the second material layers 13, 15, and 17 are alternatelylaminated. Then, outermost layers are preferably defined by the secondmaterial layers 13 and 17.

[0067] As materials constituting the first material layers 14 and 16that are sintered in the liquid phase, for example, glass orglass-ceramics composite material, is preferably used. Morespecifically, it is possible to constitute the first material layers 14using a crystalline glass, for example, an anorthite crystalline glass,a forsterite crystalline glass, cordierite crystalline glass, a celsiancrystalline glass, or various amorphous glass, for example,SiO₂—MgO—Al₂O₃ series, SiO₂—Al₂O₃ series, SiO₂—Al₂O₃—CaO series,SiO₂—Al₂O₃—BaO series, SiO₂—CaO series.

[0068] The second material layers 13, 15, and 17 are preferably composedof a material that is not sintered at the sintering temperature of thefirst material layers 14 and 16 that are sintered in the liquid phase.As such a material, an inorganic solid powder having a high meltingpoint may be used, and more specifically, Al₂O₃, BaTiO₃, ZrO₂, mullite,and other suitable materials, and mixtures thereof may be used. However,the material constituting the second material layers 13, 15, and 17 isnot limited to a ceramic material as mentioned above, but a glassmaterial is usable as long as the glass material has a sufficientlyhigher softening point than the material constituting the first materiallayers 14 and 16, and such material is not sintered during the sinteringof the first material layers.

[0069] The first inner electrode 18 and the second and third innerelectrodes 19 and 20 are arranged to define a three-terminal capacitorin the outer coating substrate 6. The first inner electrode 18 and thesecond and third inner electrodes 19 and 20 are stacked interposing thesecond material layer 15. The second inner electrode 19 has a leadingportion 19 a exposed on the side surface of the laminate, and theleading portion 19 a is electrically connected to the first outerelectrode 7. Similarly, the third inner electrode 20 has a leadingportion 20 a exposed on the side surface of the laminate, and theleading portion 20 a is electrically connected to the second outerelectrode 8.

[0070] Furthermore, the first inner electrode 18 has a leading portion18 a that extends out to the approximate center of side surface of theaforementioned laminate. The leading portion 18 a is electricallyconnected to the third outer electrode 9.

[0071] Therefore, the three-terminal capacitor is connected between thefirst to third outer electrodes 7 to 9. In particular, the first andsecond outer electrodes 7 and 8 are electrically connected,respectively, to the excitation electrode 11, the bottom surface, andthe excitation electrode on the bottom surface of the piezoelectricresonant element 2. Therefore, by connecting the first and second outerelectrodes 7 and 8 to input/output electrodes and connecting the thirdouter electrode 9 to ground, a three-terminal built in load capacitancetype piezoelectric oscillator is provided.

[0072] It is not shown in the drawing, but the upper outer coatingsubstrate 5 is arranged similar to the lower outer coating substrate 6,and in the outer coating substrate 5, a three-terminal capacitor issimilarly provided.

[0073] In the piezoelectric resonant component 1 of this preferredembodiment, the outer coating substrate 6 has a structure wherein thefirst material layers 14 and 16 and the second material layers 13, 15,and 17 are laminated, as mentioned above. In this case, the calciningtemperature, which changes due to the composition, of the first materiallayers 14 and 16, sintering in the liquid phase, is about 800° C. toabout 1000° C. when it is composed of the aforementioned material. Thatis, the first material layers 14 and 16 are calcined at a relatively lowtemperature. In this case, the material constituting the second materiallayers 13, 15, and 17 is not sintered at the calcining temperature ofthe first material layers 14 and 16 that are sintered in the liquidphase.

[0074] Therefore, the material constituting the second material layers13, 15, and 17 is penetrated into a liquid phase sintering materiallayer, and thereafter, the first material layers 14 and 16 that aresintered in the liquid phase are calcined so that the first materiallayers 14 and 16 and the second material layers 13, 15, and 17 arecombined and united firmly. In particular, the contraction of the firstmaterial layers 14 and 16 during calcination are restricted by thesecond material layers 13, 15, and 17. Then, the contraction in adirection parallel to the primary surfaces of the first material layers14 and 16 is prevented by the restriction effect of the material layers13, 15, and 17 so that it is possible to obtain an outer coatingsubstrate 6 having high dimensional precision.

[0075] Similarly, in the upper outer coating substrate 5, because it isarranged similarly to the outer coating substrate 6, the contraction ofthe first material layers during calcination are restricted by thesecond material layers functioning as the restriction material layer,then, the outer coating substrate 5 having very high dimensionalprecision can be also obtained.

[0076] Therefore, according to this preferred embodiment, because thedimensional precision of the outer coating substrates 5 and 6 is greatlyimproved, and the calcining temperatures are relatively low as mentionedabove, the costs of the outer coating substrates 5 and 6 are greatlyreduced. In the piezoelectric resonant component 1, because the outercoating substrates 5 and 6 having high dimensional precision, asmentioned above, are used, the precision of outer dimension of thepiezoelectric resonant component 1 itself is also effectively improved.

[0077] Furthermore, because the dimensional precision of the outercoating substrates 5 and 6 is greatly improved, the precision ofelectrostatic capacity of the three-terminal capacitor provided in theouter coating substrates 5 and 6, as an electronic component functionalelement, is also significantly improved.

[0078] In this preferred embodiment, the second material layer 15 isarranged between the first inner electrode 18 and the second and thirdinner electrodes 19 and 20, and, the electrostatic capacity is derivedwith the second material layer 15. However, the first material layer maybe arranged between the first inner electrode 18 and the second andthird inner electrodes 19 and 20 to define an electrostatic capacity.

[0079] In various preferred embodiments of the present invention, atleast one layer of the first material layer and the second materiallayer may be arranged, and the number of each layer, thickness, andarrangement may be appropriately changed. For example, as an outercoating substrate 31 shown in FIG. 3A, the second material layer 34 maybe arranged between the first material layers 32 and 33. As shown inFIG. 3B, reversely, the first material layer 37 may be arranged betweenthe second material layers 35 and 36. As shown in FIG. 3C, the secondmaterial layers 40 and 41 may be laminated on the top and bottom of twolayers defined by the first material layers 38 and 39.

[0080] As shown in FIG. 3D, inner electrodes 43 a to 43 c may bedisposed on the top and bottom of the second material layer 42 toconstitute a capacitor, the first material layers 44 and 45 may belaminated on the top and bottom layers thereof, and the second materiallayers 46 and 47 may be laminated on the outermost layers.

[0081] In the case in which the inner electrode is located in the outercoating substrate as mentioned above, the inner electrode may be formedby printing the conductive paste, and thereafter, may be calcined at thesame time with the outer coating substrate. The outer electrodes 7 to 9may be formed, after preparing the aforementioned laminate constitutingthe piezoelectric resonant component 1, by separately coating theconductive paste and baking, or by the thin film forming method, forexample, vapor deposition.

[0082] The aforementioned laminate may be prepared at the stage beforecalcining the outer coating substrates 5 and 6, and the laminate may becoated with the conductive paste, then, the outer electrodes 7 to 9 maybe completed by calcining at the same time with the calcining of theouter coating substrates 5 and 6.

[0083] In the first preferred embodiment, the outer electrodes 7 to 9are preferably formed by various methods as mentioned above.Furthermore, a plated film may be formed by the wet plating method onthe surface of the outer electrodes in order to improve solderabilityand other characteristics. In such a case, it is preferable that theouter coating substrates 5 and 6 are constituted using materials notcontaining a component, for example, Zr, that dissolves into a platingbath used in the wet plating. That is, as the first and second materiallayers, the aforementioned materials not containing a component thatdissolves into a plating bath are preferably used so that the outercoating substrates 5 and 6, having superior plating resistance, can beformed.

[0084] In this preferred embodiment, the outer coating substrates 5 and6 have the structure laminating the first and second material layers.However, one of the outer coating substrates may be an outer coatingsubstrate which is not an outer coating substrate constructed accordingto preferred embodiments of the present invention, for example, asubstrate made of a single material selected from ceramics,glass-ceramics, glass, or other suitable material. That is, as far as atleast one outer coating substrate is constituted according to variouspreferred embodiments of the present invention, the dimensionalprecision of the outer coating substrate, constituted according topreferred embodiments of the present invention, is still greatlyimproved. Therefore, the dimensional precision of the piezoelectricresonant component 1 is also significantly improved.

[0085]FIGS. 4A and 4B are perspective assembly views for explanation ofthe piezoelectric resonant component according to the second preferredembodiment of the present invention. In this preferred embodiment, outercoating substrates 51 and 52 are laminated on the top and bottom of thepiezoelectric resonant element 2. A concave portion 52 a is provided onthe top surface of the outer coating substrates 52. A concave portion,not shown in the drawing, is similarly formed on the bottom surface ofthe outer coating substrates 51. The concave portion 52 a is arranged todefine a space that allows for free and unhindered vibration of theenergy trap resonant portion of the piezoelectric resonant element.

[0086]FIG. 4B is a perspective assembly view of the outer coatingsubstrate 52. In the outer coating substrate 52, similar to the outercoating substrate 6 according to the first preferred embodiment, thefirst to third inner electrodes 18 to 20 are arranged inside.

[0087] The outer coating substrate 52 has a structure wherein theaforementioned inner electrodes 18 to 20 and material layers 53 to 60are laminated together. Among these, the material layers 53, 55, 56, 58,and 60 are the second material layers, and the material layers 54, 57,and 59 are the first material layers.

[0088] The material layers 53 to 55, constituted to have, respectively,a plan shaped, substantially rectangular frame, have substantiallyrectangular openings 53 a to 55 a. The openings 53 a to 55 a arearranged to define the aforementioned concave portion 52 a.

[0089] Regarding other points, because of the similarity to the firstpreferred embodiment, explanations about the same elements are omittedand similar reference numerals are used to represent similar elements.In this preferred embodiment, also, the upper outer coating substrate 51is arranged similarly to the lower outer coating substrate 52. However,the upper outer coating substrate 51 may be composed of an outer coatingsubstrate that is not the outer coating substrate constructed accordingto preferred embodiments of the present invention.

[0090] In the second preferred embodiment, because, similarly to thefirst preferred embodiment, the outer coating substrate 52 has astructure wherein the first material layers 54, 57, and 59 and thesecond material layers 53, 55, 56, 58, and 60 are laminated, thedimensional precision is greatly improved, and the precision ofelectrostatic capacity of the three-terminal capacitor is alsosignificantly improved. Furthermore, the outer coating substrate 52 canbe calcined at a low temperature.

[0091] Therefore, similarly to the first preferred embodiment, in thepiezoelectric resonant component 51, it is possible to improve thedimensional precision, to reduce the cost, and to reduce the dispersionof electrostatic capacity.

[0092]FIG. 5 and FIG. 6 are a perspective assembly view for explanationof a piezoelectric resonant component according to the third preferredembodiment of the present invention and a perspective assembly view forexplanation of an outer coating substrate.

[0093] In the piezoelectric resonant component according to thispreferred embodiment, an energy trap piezoelectric resonant element 71using the thickness slip mode is stored in a package including outercoating substrates 72 and 73. The outer coating substrate 72 has astorage concave 72 a. The storage concave 72 a is opened in the topsurface of the outer coating substrate 72, and is constituted to have asize where the piezoelectric resonant element 71 can be stored. Thefirst and second outer electrodes 7 and 8 are arranged to extend fromthe bottom surface of the storage concave 72 a to the side surface ofthe outer coating substrate 72. The third outer electrode 9 is locatedin the approximate center of the side surface of the outer coatingsubstrate 72. The first to third outer electrodes 7 to 9 are not onlyexposed on the side surface of the outer coating substrate 72 but alsoarranged to extend from the side surface to the opposite side surfacevia the bottom surface.

[0094] On the other hand, the first excitation electrode 74 is formed onthe top surface of the piezoelectric resonant element 71. An excitationelectrode is also formed on the bottom surface in order to face theexcitation electrode 74 in the approximate center of the piezoelectricresonant element 71, wherein these electrodes are correspondinglypositioned on the top and bottom surfaces. The excitation electrode onthe bottom surface is extended to the right in FIG. 5, and iselectrically connected to the outer electrode 8 exposed in the storageconcave 72 a via a conductive junction member 75. The excitationelectrode 74 is disposed on the top surface of the piezoelectricresonant element 71, and, at one end of the piezoelectric resonantelement 71, is extended from the end surface to the bottom surface. Theextended component of the excitation electrode 74 on the bottom surfaceis electrically connected to the outer electrode 7 exposed in thestorage concave 72 a via a conductive junction member 76. Thepiezoelectric resonant element 71 is stored in the storage concaveinterposing the conductive junction members 75 and 76, and is fixed.

[0095] On the other hand, the resonant portion of the piezoelectricresonant element 71 is positioned at the approximate center inlongitudinal direction, and, in this preferred embodiment, due to thethickness of the aforementioned conductive junction members 75 and 76, aspace for allowing for free and unhindered vibration is constitutedbelow the resonant portion.

[0096] The outer coating substrate 73, in the shape of a cap, has anopening (not shown in the drawing) has opening facing downward, and theopening periphery is joined to the outer coating substrate 72 by aninsulating adhesive (not shown in the drawing).

[0097] This preferred embodiment is characterized in that the outercoating substrate 72 is constituted according to preferred embodimentsof the present invention.

[0098] Materials for the cap are not particularly limited, and ceramics,for example, alumina, resins, metals, and other suitable materials, areusable. Metals are suitable for achieving miniaturization and ease ofshaping. Metallic materials are not particularly limited, and 42Nialloys, aluminum alloys, nickel silver, and other suitable metals, areusable.

[0099] As shown in FIG. 6, the outer coating substrate 72 is constitutedby laminating material layers 81 to 88, wherein inner electrodes 18 to20 and outer electrodes 7 and 8 are interposed. Among the materiallayers 81 to 88, material layers 82, 85, and 87 are the first materiallayers, and material layers 81, 83, 84, 86, and 88 are the secondmaterial layers. In the material layers 81 to 83, substantiallyrectangular openings 81 a to 83 a are formed, respectively, to definethe aforementioned concave 72 a.

[0100] Parts of the outer electrodes 7 and 8, interposed between thematerial layers 83 and 84, are formed by the coating and baking of theconductive paste. The baking of the conductive paste is conducted,similarly to the inner electrodes 18 to 20, when the outer coatingsubstrate 72 is calcined.

[0101] The inner electrodes 18 to 20 are constituted similarly to theinner electrodes 18 to 20 according to the first preferred embodiment.

[0102] Notches 89 are preferably formed in both side surfaces of thematerial layers 84 to 88, and the notches 89 are filled with theconductive paste. The paste is baked to constitute parts of the outerelectrodes 7 to 9 which are exposed on the side surface of the outercoating substrate 72.

[0103] The parts of the outer electrodes 7 to 9, located on the sidesurface of the outer coating substrate 72, may be formed, aftercalcining the outer coating substrate 72, by an arbitrary method, forexample, by the coating and baking of the conductive paste, or by thethin film forming method, for example, vapor deposition, plating, orsputtering.

[0104] However, as in this preferred embodiment, because the outerelectrodes 7 to 9 are formed at the same time with the calcination ofthe outer coating substrate 72, by filling the notches with theconductive paste and forming parts of the outer electrodes 7 to 9 on theside surface, parts to be exposed in the storage concave 72 a, and partsto be positioned on the bottom surface of the material layer 88, duringthe calcining of the outer coating substrate 72, i.e., by thesimultaneous calcining method, simplification of the manufacturingprocess is achieved.

[0105] In the third preferred embodiment, because the outer coatingsubstrate 72 is constituted according to preferred embodiments of thepresent invention, the dimensional precision of the outer coatingsubstrate 72 is greatly improved, and the cost of the outer coatingsubstrate 72 is significantly reduced. Therefore, the dimensionalprecision of the piezoelectric resonant component is also greatlyimproved. Furthermore, the dispersion of electrostatic capacity of thethree-terminal capacitor included in the outer coating substrate 72 isalso greatly reduced.

[0106] In the first to third preferred embodiments, the outer coatingsubstrates and the piezoelectric resonant components according to thepresent invention are explained with reference to the perspectiveassembly view of only one piezoelectric resonant component. However, theouter coating substrates and the piezoelectric resonant componentsaccording to preferred embodiments of the present invention may bemanufactured in the state of a mother substrate, thereafter, cut,finally or before calcining, into individual outer coating substrates orpiezoelectric resonant component units. In the case in whichconventional outer coating substrates are used, due to the contractionduring the calcination, the dimensional precision of the aforementionedconcave 72 is dispersed so that the numbers of outer coating substratespossible to be cut out of one mother substrate was restricted.Furthermore, an extra margin area, corresponding to generated dispersionin the dimension of the concave portion of each piezoelectric resonantcomponent and storage concave, and dispersion in the dimension of outercoating substrates, had to be formed in the mother substrate. Therefore,there was a problem that the dimension of finally obtained piezoelectricresonant component was become large.

[0107] On the other hand, in the case in which the outer coatingsubstrates according to preferred embodiments of the present inventionis used, as mentioned above, because the dimensional precision isgreatly improved, the dimensional precision of the concave portion orthe storage concave is significantly improved, the numbers of individualouter coating substrates or piezoelectric resonant components cut out ofone mother substrate can be increased, and the miniaturization of outercoating substrate and piezoelectric resonant component can also beachieved.

[0108] In the outer coating substrate according to preferred embodimentsof the present invention, by changing the thickness of the first andsecond material layers and the arrangement of the inner electrodes,outer coating substrates having various properties and characteristicscan be provided.

[0109] For example, in an outer coating substrate 90 shown in FIG. 7,inner electrodes 18 to 20 are stacked interposing the second materiallayer 91 having a high dielectric constant in order to constitute athree-terminal capacitor. Therefore, a capacitor having a largeelectrostatic capacity can be constituted. Then, the first materiallayers 92 a and 92 b, sintering in the liquid phase, are laminated onthe top and bottom of the second material layer 91. On the outside ofthe first material layers 92 a and 92 b, the second material layers 93 aand 93 b having a smaller thickness than the first material layers 92 aand 92 b are laminated. In this case, centered second material layer 91is preferably composed of a high dielectric constant material, forexample, a barium titanate dielectric ceramic material, to obtain alarge electrostatic capacity. That is, the second material layer 91 andthe second material layers 93 a and 93 b may be differentiated inconstituent materials as mentioned above.

[0110] In an outer coating substrate shown in FIG. 8, the secondmaterial layers 95 a and 95 b are provided on the top and bottom of thefirst material layer 94, and an electrode 96 is disposed only on the topthereof. Therefore, during calcination, there is a risk of becomingconvex downward due to bending as shown in FIG. 8. In this case, asshown in FIG. 9, the second material layer 95 a on the top of the firstmaterial layer 94 may be composed of a material having a differentthermal expansion coefficient from the second material layer 95 b on thebottom of the first material layer 94. That is, by making the thermalexpansion coefficient of the second material layer 95 a smaller than thethermal expansion coefficient of the second material layer 95 b, warpingof an outer coating substrate 97 is prevented.

[0111] In the first to third preferred embodiments, the capacitor islocated in the outer coating substrate. However, a resistive element oran inductance element may be provided by arranging a resistive materialor a magnetic material inside, respectively. That is, it is possible toconstitute various electronic component functional elements, and it ispossible to build in the electronic component functional element havingsmall dispersion electric characteristics in the outer coatingsubstrate.

[0112] In the first and second preferred embodiments, the first andsecond outer coating substrates are laminated on the top and bottom ofone piezoelectric resonant element. However, a plurality ofpiezoelectric resonant elements may be laminated, and the first andsecond outer coating substrates may be laminated on the top and bottomof the laminate. Inner coating substrates may be interposed between theplurality of piezoelectric resonant elements.

[0113] As mentioned above, the outer coating substrates according topreferred embodiments of the present invention are preferably used inpiezoelectric resonant components. Furthermore, the outer coatingsubstrates can be widely used for other electronic components thanpiezoelectric resonant components, then, it is possible to improve thedimensional precision of electronic components, to reduce the cost, andto stabilize electric characteristics when circuits of the capacitor orinductance are constituted in outer coating substrates.

[0114]FIGS. 13A and 13B are a sectional view and a perspective externalappearance of a piezoelectric resonant component according to the fourthpreferred embodiment of the present invention.

[0115] In a piezoelectric resonant component 101, the first and secondpackage substrates 103 and 104 are laminated on the top and bottom of asubstantially rectangular piezoelectric resonant element 102.

[0116] In the piezoelectric resonant component 101, the first and secondexcitation electrodes 106 and 107 are provided on both the primarysurfaces of the piezoelectric substrate 105. The piezoelectric substrate105 is preferably made of a piezoelectric ceramic material, for example,a lead zirconate titanate ceramic, or a piezoelectric single crystal,for example, a crystal. The Young's moduli of these kinds ofpiezoelectric materials are normally about 5.0×10¹⁰ to about 18×10¹⁰. Inthe case in which the triple wave is used, piezoelectric materialshaving the Young's moduli of about 14.2×10¹⁰ to about 16.2×10¹⁰ arepreferably used.

[0117] The excitation electrodes 106 and 107 are arranged to face eachother on the top and bottom surfaces at the approximate center of thepiezoelectric plate 105, and the portion where the excitation electrodes106 and 107 are arranged to face each other, constitutes an energy trappiezoelectric resonant component. The excitation electrode 106 is ledout to one end surface of a structure wherein the piezoelectric resonantelement 102, and the package substrate 103 and 104 are laminated, andthe excitation electrode 107 is led out to the other end surface. Onboth end surfaces of the aforementioned laminated structure, outerelectrodes 108 and 109 are provided, respectively.

[0118] The excitation electrodes 106 and 107 are preferably formed byputting on a conductive material, for example, Ag, or Cu, using the thinfilm forming method, for example, the vapor deposition, the plating, orthe sputtering.

[0119] On the other hand, the outer electrodes 108 and 109 arepreferably formed by a similar method or by coating and hardening aconductive paste.

[0120] The package substrates 103 and 104 have concave portions 103 aand 104 a in the surface laminated on the piezoelectric resonant element102. The concave portions 103 a and 104 a are arranged to define spacesthat allow for free and unhindered vibration of the resonant portion ofthe piezoelectric resonant element 102.

[0121] As not shown in FIG. 13, the aforementioned package substrates103 and 104 are fixed on the piezoelectric resonant element 102 via ajunction member preferably made of an insulating adhesive.

[0122] The aforementioned package substrates 103 and 104 are preferablymade of an insulating material having a lower Young's modulus than aYoung's modulus of a piezoelectric material. As the insulating material,insulating ceramics, for example, Al₂O₃ and MgTiO₃, or a composite ofamorphous glass and ceramic powder, or other suitable material., areusable. The Young's moduli of the package substrates 103 and 104 are notparticularly limited as far as being lower than the Young's modulus ofthe piezoelectric material, and package substrates having the Young'smoduli of about 9.8×10¹⁰ to about 11.8×10¹⁰ are preferably used.

[0123] Therefore, the ratio of the Young's modulus of the packagesubstrate to the Young's modulus of the piezoelectric resonant element102 is preferably within the range of about 0.60 to about 0.83.

[0124] In this preferred embodiment, the spurious vibration generated inthe piezoelectric resonant element 102 is propagated to the packagesubstrates 103 and 104 via a junction member (not shown in the drawing).However, because the Young's moduli of the package substrates 103 and104 are relatively small, the spurious vibration is attenuated.Therefore, it is possible to effectively suppress the spuriousnessappearing in resonant characteristics.

[0125] The aforementioned spuriousness suppression effect is obtained aslong as the Young's moduli of the package substrates 103 and 104 aresmaller than the Young's modulus of the piezoelectric materialconstituting the piezoelectric resonant element 102. Furthermore, whenthe Young's moduli of the package substrates 103 and 104 are within theaforementioned preferable range, the spuriousness can be moreeffectively suppressed.

[0126] For example, in the case in which a lead zirconate titanatepiezoelectric ceramics is used as the piezoelectric material, theYoung's modulus is about 15.2×10¹⁰. In the case in which the one made ofa composite of SiO₂—MgO—Al₂O₃ as an amorphous glass and Al₂O₃, BaTiO₃,or ZrO₂ as ceramic powder is used as the package substrates 103 and 104,the Young's modulus is about 10.8×10¹⁰, and in the case in which Al₂O₃96% in purity is used, the Young's modulus, changing due to the purity,is about 32.0×10¹⁰.

[0127]FIG. 14 is a sectional view of a piezoelectric resonant componentaccording to the fifth preferred embodiment of the present invention.

[0128] In the piezoelectric resonant component 111 according to thefifth preferred embodiment, an energy trap piezoelectric resonantelement 102 is joined on a package substrate 112 on a substrate, viaconductive junction members 113 and 114, and is fixed to the packagesubstrate 112. An excitation electrode 106 is arranged on the endsurface of a piezoelectric plate 105 and arranged to extend the bottomsurface, and a component of the excitation electrode 106 on the bottomsurface of the piezoelectric plate 105 is joined on a package substrate112 with the conductive junction member 113.

[0129] On the top surface of the package substrate 112, terminalelectrodes 115 and 116 extend to outside thereof are provided. Theterminal electrodes 115 and 116 are joined to the aforementionedconductive junction members 113 and 114.

[0130] Also, a cap 117 is joined on the package substrate 112. The cap117 has an opening downward, and is joined on the package substrate 112via an insulating adhesive (not shown in the drawing), surrounding thepiezoelectric resonant element 102.

[0131] The cap 117 is preferably made of a material in which at least asurface is conductive, for example, a metal or a structure made bycovering a surface of insulating material with a conductive film. Byusing such a cap 117 having a conductive surface, the piezoelectricresonant element 102 is electromagnetically shielded. However, the cap117 may be composed of an insulating material or other suitablematerial.

[0132] In this preferred embodiment, also, the Young's modulus of thepackage substrate 112 is preferably less than the Young's modulus of thepiezoelectric material constituting the piezoelectric plate 105 of thepiezoelectric resonant element 102. Therefore, similarly to the fourthpreferred embodiment, in the case in which the undesired spuriousvibration generated in the piezoelectric resonant element 102 ispropagated to the package substrate 112 via conductive junction members113 and 114, the vibration is attenuated by the package substrate 112.Therefore, the undesired spuriousness in resonant characteristics iseffectively suppressed.

[0133]FIG. 15 is a sectional view of a piezoelectric resonant componentaccording to the sixth preferred embodiment of the present invention. Inthe piezoelectric resonant component 121 according to this preferredembodiment, a package substrate 122 has a concave portion 122 a, and apiezoelectric resonant element 102 is stored in the concave portion 122a. That is, the package substrate 122 has an opening opened upward, andthe inside of the opening constitutes the concave portion 122 a. In theconcave portion 122 a, similarly to the fifth preferred embodiment, thepiezoelectric resonant element 102 is fixed to the package substrate 122via conductive junction members 113 and 114. A covering member 123 isjoined on the end surface of opening of the package substrate 122 via anadhesive, not shown in the drawing, in order to close the concaveportion 122 a.

[0134] This preferred embodiment is constituted similarly to the fifthpreferred embodiment, except that the package substrate 122 having theconcave portion 122 a is used instead of the package substrate 112, andthe covering member 123 is used instead of the cap 117. That is, theYoung's modulus of the package substrate 122 is smaller than the Young'smodulus of the piezoelectric material constituting the piezoelectricplate 105 of the piezoelectric resonant element 102. Therefore,similarly to the fifth preferred embodiment, the undesired spuriousnessgenerated in the piezoelectric resonant element 102 is attenuated in thepackage substrate 122, and the spuriousness appearing in resonantcharacteristics is effectively suppressed.

[0135] In the aforementioned fourth to sixth preferred embodiments, byselecting a piezoelectric resonant element and a Young's modulus ofpackage substrate, the undesired spuriousness is effectively suppressedas mentioned above. Therefore, the piezoelectric resonant componentsaccording to the fourth to sixth preferred embodiments are easilymanufactured, and the undesired spuriousness is suppressed withoutincreasing the cost of piezoelectric resonant component.

[0136]FIG. 16 is a sectional view of a piezoelectric resonant componentaccording to the seventh preferred embodiment of the present invention.

[0137] In the piezoelectric resonant component 131 according to theseventh preferred embodiment, the first and second package substrates132 and 133 are laminated on the top and bottom of the piezoelectricresonant element 102. The seventh preferred embodiment is different fromthe fourth preferred embodiment in that the first and second packagesubstrates 132 and 133 preferably include multi-layered packagesubstrates in which a plurality of material layers are laminated.Regarding other points, because of the similarity to the fourthpreferred embodiment, detailed explanations of the same elements of thefourth preferred embodiment are omitted except for using the samereference numerals for similar elements.

[0138] The package substrate 132 has a structure in which the first tofifth material layers 132 a to 132 e are laminated together. Amongthese, the first, third, and fifth material layers 132 a, 132 c, and 132e are preferably made of SiO₂—MgO—Al₂O₃, and the second and fourthmaterial layers 132 b and 132 d are preferably made of Al₂O₃. Therefore,the Young's modulus of SiO₂—MgO—Al₂O₃ constituting the first, third, andfifth material layers 132 a, 132 c, and 132 e is about 8.01×10¹⁰, andthe Young's modulus of Al₂O₃ constituting the second and fourth materiallayers 132 b and 132 d is about 32.0×10¹⁰. By controlling the thicknessof the first, third, and fifth material layers 132 a, 132 c, and 132 eand the thickness of the second and fourth material layers 132 b and 132d, in this preferred embodiment, the Young's modulus of the firstpackage substrate 132 as a whole is about 10.8×10¹⁰. Similarly, thepackage substrate 133 also has a structure laminating the first to fifthmaterial layers 132 a to 132 e, and the Young's modulus as a whole isabout 10.8×10¹⁰.

[0139] On the other hand, the piezoelectric plate 105 of thepiezoelectric resonant element 102 includes a lead zirconate titanateceramics, and its Young's modulus is about 15.2×10¹⁰.

[0140] That is, the ratio of the Young's modulus of the packagesubstrate 132 and 133 to the Young's modulus of the piezoelectricmaterial is about 0.71. Therefore, similarly to the preferable exampleof the fourth preferred embodiment, in the case in which the spuriousvibration generated in the piezoelectric resonant element 102 ispropagated to the package substrates 132 and 133 via junction membersnot shown in the drawing, the spurious vibration is attenuated by thepackage substrates 132 and 133, and the undesired spuriousness appearingin resonant characteristics can be effectively suppressed.

[0141] The aforementioned package substrates 132 and 133 can be easilyobtained by laminating and calcining a green sheet, primarily composedof a material made of amorphous glass and ceramic powder, and a greensheet made of Al₂O₃. That is, these can be easily obtained using themanufacturing method for ceramics multi-layered substrates. Therefore,the cost of the piezoelectric resonant component 131 is not increased.

[0142]FIG. 17 is a sectional view of a piezoelectric resonant componentaccording to the eighth preferred embodiment of the present invention.In the piezoelectric resonant component 141, the first and secondpackage substrates 142 and 143 are laminated on both primary surfaces ofthe piezoelectric resonant element 102. The eighth preferred embodimentis constituted similarly to the seventh preferred embodiment except thatthe structures of package substrates 142 and 143 are different from theseventh preferred embodiment.

[0143] That is, the first and second package substrates 142 and 143 aremulti-layered package substrates. However, the multi-layered structuresare differentiated from the package substrates 132 and 133 shown in FIG.16.

[0144] The first package substrate 142 is taken as an example. The firstpackage substrate 142 has a concave portion 142 a for allowing for freeand unhindered vibration of the resonant portion of the piezoelectricresonant element 102. The package substrate 142 has the first to thirdmaterial layers 142 b to 142 d. The material layers 142 b to 142 d areeach arranged to surround the aforementioned concave portion 142 a. Inother words, in the sectional view shown in FIG. 17, the first to thirdmaterial layers 142 b to 142 d are each shaped like a symbol “],”wherein the end potion is constituted to reach the component joined tothe piezoelectric resonant element 102. This is similar in the packagesubstrate 143. Thus, when the package substrates 142 and 143 aremulti-layered structures, each material layer can be constituted invarious forms.

[0145] In the eighth preferred embodiment, because the Young's modulusof the first and second package substrates 142 and 143 as a whole isless than the Young's modulus of the piezoelectric material constitutingthe piezoelectric resonant element 102, similarly to the fourth toseventh preferred embodiment, the spurious vibration is attenuated inthe package substrates 142 and 143, and, as a result, the undesiredspuriousness appearing in resonant characteristics is effectivelysuppressed.

[0146]FIG. 18 is a sectional view of a piezoelectric resonant componentaccording to the ninth preferred embodiment of the present invention.

[0147] The piezoelectric resonant component 151 corresponds to amodification of the fifth preferred embodiment, and is different only inthat a multi-layered package substrate 152 is used instead of thepackage substrate 112 used in the fifth preferred embodiment.

[0148] The package substrate 152 has a structure in which the first tothird material layers 152 a to 152 c is laminated. The first and thirdmaterial layers 152 a and 152 c are preferably made of SiO₂—MgO—Al₂O₃,and the second material layer 152 b is preferably made of Al₂O₃. Bycontrolling the thickness of the material layers, in this preferredembodiment, the Young's modulus of the package substrate 152 as a wholeis about 10.8×10¹⁰. Then, the ratio of the Young's modulus of thepackage substrate 152 to the Young's modulus of the piezoelectricmaterial is about 0.71.

[0149] Therefore, similarly to the fourth to eighth preferredembodiments, the spurious vibration generated in the piezoelectricresonant element 102 can be attenuated in the package substrate 152,and, as a result, the spuriousness appearing in resonant characteristicscan be effectively suppressed.

[0150]FIG. 19 is a sectional view of a piezoelectric resonant componentaccording to the tenth preferred embodiment of the present invention.The piezoelectric resonant component 161 corresponds to a modificationof the sixth preferred embodiment, and is different in only that amulti-layered package substrate 162 is used instead of the packagesubstrate 122.

[0151] The multi-layered package substrate 162 has a structure in whichthe first to fifth material layers 162 a to 162 e laminated. The first,third, and fifth material layers 162 a, 162 c, and 162 e are preferablymade of SiO₂—MgO—Al₂O₃, and the second and fourth material layers 162 band 162 d are preferably made of Al₂O₃. By controlling the thickness ofthe first to fifth material layers 162 a to 162 e, the Young's modulusof the package substrate 162 as a whole is about 10.8×10₁₀.

[0152] Therefore, the ratio of the Young's modulus of the packagesubstrate to the Young's modulus of the piezoelectric material is about0.71 and, similarly to the fourth to ninth preferred embodiments, thespurious vibration generated in the piezoelectric resonant element 102is attenuated in the package substrate 162. Then, the undesiredspuriousness appearing in resonant characteristics can be effectivelysuppressed.

[0153] In the aforementioned fourth to ninth preferred embodiments, thecase, in which the energy trap piezoelectric resonant element 102 isused, is taken as an example and is explained. However, in preferredembodiments of the present invention, a piezoelectric filter element,wherein a plurality of energy trap resonant portions are constituted,may be used as the aforementioned piezoelectric resonant element.

[0154] Furthermore, electrodes may be formed as a component of apiezoelectric resonant element, and besides a piezoelectric resonantportion, other electronic component function portion, for example, acapacitor portion, may be constituted.

[0155] In the outer coating substrate for an electronic componentaccording to preferred embodiments of the present invention, because thefirst material layer that is sintered in the liquid phase and the secondmaterial layer that is not sintered at the sintering temperature of thefirst material layer are laminated, and are calcined at a temperature atwhich the first material layer is sintered, the low temperaturecalcination is possible. Therefore, the cost of the outer coatingsubstrate is greatly reduced.

[0156] Because the first material layer that is sintered in the liquidphase is superior in mechanical strength, and has a flexural strength ofabout 200 kg/cm² to about 2500 kg/cm², an outer coating substrate havinga higher flexural strength than conventional dielectric ceramics havinga flexural strength of about 800 kg/cm² to about 1500 kg/cm², and havingsuperior mechanical strength can be constituted.

[0157] Furthermore, the second material layer is laminated on the firstmaterial layer, and because the second material layer functions as arestriction material layer during the calcination of the first materiallayer, the contraction of the first material layer during thecalcination is restricted, then the substrate precision is extremelyimproved. Therefore, the outer coating substrate having superiordimensional precision is provided, and the thinning and miniaturizationof the outer coating substrate and, furthermore, the electroniccomponent using the outer coating substrate are achieved.

[0158] In the case in which the first material layer is composed ofglass or glass-ceramics, it is possible to be calcined at a relativelylow temperature of about 800° C. to about 1000° C., and it is possibleto effectively reduce the cost of the outer coating substrate.

[0159] In the case in which the outer coating substrate does not containa component that is dissolved into a wet plating bath, because theplating resistance of the outer coating substrate is improved, forexample, by forming an outer electrode on the outer surface of the outercoating substrate and, furthermore, forming a plated film, thereliability of the outer coating substrate and, furthermore, theelectronic component is greatly increased.

[0160] In the case in which a concave portion is provided on at leastone primary surface of an outer coating substrate, by using the concaveportion, it is possible to store an electronic component element, forexample, a piezoelectric resonant element, or to form a space thatallows for free and unhindered vibration of resonant portion of anenergy trap piezoelectric resonant element.

[0161] In the case in which at least one pair of capacitive electrodes,interposing at least a component of the first or second material layer,is provided, and a capacitor is defined by the pair of capacitiveelectrodes, because the dimensional precision of an outer coatingsubstrate is improved, the precision of an electrostatic capacity of thecondenser is also improved. In particular, in the case in which one pairof capacitive electrodes, arranged to face each other and interpose atleast a component of the second material layer, is provided, ceramicshaving a high dielectric constant can be used as the second materiallayer, then, it is possible to achieve a large electrostatic capacity.

[0162] In the case in which a resistive element and an inductanceelement in an outer coating substrate are composed of a resistivematerial and a magnetic material, by improving the dimensional precisionof the substrate, the resistive element and the inductance elementhaving superior precision of the resistance and inductance can beconstituted.

[0163] In the case in which at least two first material layers arelaminated, the mechanical strength of outer coating substrates iseffectively improved because of the plurality of first material layers,and the thinning of the outer coating substrate is achieved.

[0164] In the piezoelectric resonant component according to preferredembodiments of the present invention, because at least one of the firstand second outer coating substrates includes the outer coating substratefor electronic components according to preferred embodiments of thepresent invention, the mechanical strength and the dimensional precisionof the outer coating substrate are greatly improved. Therefore, thedimensional precision and the mechanical strength of the entirepiezoelectric resonant component are improved, and because the outercoating substrate can be calcined at a low temperature, the cost ofpiezoelectric resonant component is reduced.

[0165] Furthermore, due to the improvement of the dimensional precisionof the outer coating substrate, the dispersion of the characteristics ofpiezoelectric resonant component is also reduced.

[0166] In the case in which a piezoelectric resonant element is anenergy trap piezoelectric resonant element, and the first and secondouter coating substrates are laminated on the piezoelectric resonantelement so as to define a space for allowing for free and unhinderedvibration of the resonant portion of the energy trap piezoelectricresonant element, according to preferred embodiments of the presentinvention, the energy trap piezoelectric resonant component havingsuperior dimensional precision, having a high mechanical strength, andcapable of being inexpensively prepared, can be provided.

[0167] In the case in which a concave portion is disposed on a surfaceand laminated on a piezoelectric resonant element, of at least one ofthe first and second outer coating substrates, a space for allowing forfree and unhindered vibration is defined by the concave portion.

[0168] In the piezoelectric resonant component according to preferredembodiments of the present invention, in the case in which the firstmaterial layer is composed of glass or glass-ceramics, it is possible tocalcine at a relatively low temperature of about 800° C. to about 1000°C., and the cost of outer coating substrate can be effectively reduced.

[0169] In the piezoelectric resonant component according to preferredembodiments of the present invention, in the case in which the first andsecond outer coating substrates do not contain a component thatdissolves into a wet plating bath, because the plating resistance of theouter coating substrate is improved, for example, by forming an outerelectrode on the outer surface of the outer coating substrate and,furthermore, forming a plated film, the reliability of the outer coatingsubstrate and, furthermore, the electronic component are greatlyincreased.

[0170] In the case in which, in at least one of the first and secondouter coating substrates of the piezoelectric resonant component ofpreferred embodiments of the present invention, furthermore, at leastone pair of capacitive electrodes arranged to interpose at least acomponent of the first material layer is provided, a capacitor isdefined by the pair of capacitive electrodes. Then, the dispersion ofelectrostatic capacity of the capacitor is reduced due to theimprovement of the dimensional precision of the outer coating substrate.Therefore, a built-in capacitor type piezoelectric resonant componenthaving a small dispersion of electrostatic capacity of the capacitor isprovided.

[0171] In the piezoelectric resonant component according to preferredembodiments of the present invention, in the case in which a resistiveelement and an inductance element in an outer coating substrate arecomposed of a resistive material and a magnetic material, by improvingthe dimensional precision of the substrate, the resistive element andthe inductance element having superior precision of the resistance andinductance can be constituted.

[0172] In the case in which at least one of the first and second outercoating substrates of the piezoelectric resonant component of preferredembodiments of the present invention has a plurality of first materiallayers, the mechanical strength of the outer coating substrate iseffectively improved because of the plurality of first material layers,and the thinning of the outer coating substrate is achieved.

[0173] In the piezoelectric resonant component according to preferredembodiments of the present invention, because the Young's modulus of thepackage substrate is less than the Young's modulus of the piezoelectricmaterial constituting the piezoelectric resonant element, in the case inwhich the spurious vibration generated in the piezoelectric resonantelement is propagated to the package substrate via junction members, thespurious vibration is attenuated in the package substrate. Therefore,the undesired spuriousness appearing in resonant characteristics andfilter characteristics can be effectively suppressed.

[0174] In the present invention, as mentioned above, because theundesired spuriousness can be effectively suppressed by controlling theYoung's modulus of the piezoelectric material constituting the packagesubstrate and the piezoelectric resonant element, the manufacturingprocess is greatly simplified, and the increase in cost of thepiezoelectric resonant component is prevented.

[0175] Therefore, it becomes possible to easily and inexpensivelyprovide a piezoelectric resonant component generating no undesiredspuriousness, and having superior characteristics.

[0176] In the case in which the aforementioned package substrateincludes a multi-layered package substrate having at least two layers,by controlling the number of layers, thickness, and othercharacteristics of the materials constituting each layer, the packagesubstrate having a smaller Young's modulus compared to piezoelectricmaterials, and being able to effectively suppress the undesiredspuriousness can be easily constituted.

[0177] In the case in which a multi-layered package substrate has alayer, having a larger Young's modulus than a Young's modulus ofpiezoelectric material, and a layer, having a smaller Young's modulusthan the piezoelectric material, as far as the Young's modulus as awhole is specified at the smaller value than the Young's modulus of thepiezoelectric material, the multi-layered package substrate can becomposed of various materials. For example, by laminating layers made ofmaterials having a large Young's modulus but having superior heatresistance and dimension stability, the dimension stability, the heatresistance, and other characteristics, of the piezoelectric resonantcomponent are greatly improved.

[0178] Such a structure can be attained when, for example, the layerhaving a small Young's modulus is made of a composite of amorphous glassand ceramic powder, and the layer having a large Young's modulus usesAl₂O₃ or MgTiO_(3.)

[0179] In the case in which the piezoelectric resonant element is anenergy trap piezoelectric resonant element having an energy trapresonant portion, according to preferred embodiments of the presentinvention, an energy trap piezoelectric resonant component generatingminimal undesired spuriousness, and being inexpensive can be provided.

[0180] In the case in which package substrates are laminated on bothsurfaces of a piezoelectric resonant element, the undesired spuriousnesscan be effectively suppressed on the both surfaces of the piezoelectricresonant element.

[0181] In the case in which a piezoelectric resonant element is fixed ona package substrate, and a cap member is joined to the package substratesurrounding the piezoelectric resonant element, the undesiredspuriousness can be suppressed by the package substrate, and thepiezoelectric resonant element can be surely sealed in the packagestructure, composed of the package substrate and the cap, by the capmember.

[0182] Similarly, in the case in which a package substrate has a concaveportion to store a piezoelectric resonant element, and a cover member isfixed to the package member, the undesired spuriousness can besuppressed by the package substrate, and the piezoelectric resonantelement can be surely sealed in the package structure, composed of thepackage substrate and the covering member.

[0183] While the invention has been described with reference topreferred embodiments thereof, many modifications and variations of thepresent invention are possible in light of the above teachings. It istherefore to be understood that within the scope of the appended claims,the invention may be practiced otherwise than as specifically described.

What is claimed is:
 1. An outer coating substrate for an electroniccomponent, comprising: a multi-layered substrate having a first materiallayer and a second material layer laminated together; wherein the firstmaterial layer is capable of being sintered in a liquid phase and thesecond material layer is not capable of being sintered at the sinteringtemperature of the first material layer.
 2. An outer coating substratefor an electronic component according to claim 1 , wherein said firstmaterial layer is made of one of glass and glass-ceramics.
 3. An outercoating substrate for an electronic component according to claim 1 ,wherein said substrate does not contain a component that is capable ofdissolving into a wet plating bath.
 4. An outer coating substrate for anelectronic component according to claim 1 , wherein a concave portion isprovided on at least one primary surface of said substrate.
 5. An outercoating substrate for an electronic component according to claim 1 ,wherein said substrate has at least one pair of capacitive electrodesarranged to face each other and interposing at least a portion of saidsecond material layer, and a capacitor is defined by said pair ofcapacitive electrodes.
 6. An outer coating substrate for an electroniccomponent according to claim 1 , wherein a resistive element and aninductance element are provided in said substrate and are composed of aresistive material and a magnetic material.
 7. An outer coatingsubstrate for an electronic component according to claim 1 , wherein atleast two layers of said first material layer are laminated togetherwith said second material layer.
 8. A piezoelectric resonant component,comprising: a piezoelectric resonant element; first and second outercoating substrates laminated on the top and bottom of said piezoelectricresonant element; wherein at least one of said first and second outercoating substrates includes a multi-layered substrate having a laminatestructure defined by a first material layer and a second material layer,the first material layer is capable of being sintered in a liquid phaseand the second material layer is not capable of being sintered at thesintering temperature of said first material layer.
 9. A piezoelectricresonant component according to claim 8 , wherein said piezoelectricresonant element is an energy trap piezoelectric resonant element, andsaid first and second outer coating substrates are laminated on saidpiezoelectric resonant element so as to define a space for allowing forfree and unhindered vibration of a resonant portion of said energy trappiezoelectric resonant element.
 10. A piezoelectric resonant componentaccording to claim 9 , wherein a concave portion is disposed on asurface of at least one of said first and second outer coatingsubstrates and said space is defined by said concave portion.
 11. Apiezoelectric resonant component according to claim 8 , wherein saidfirst material layer is made of one of glass and glass-ceramics.
 12. Apiezoelectric resonant component according to claim 8 , wherein saidfirst and second outer coating substrates do not contain a componentthat is capable of dissolving into a wet plating bath.
 13. Apiezoelectric resonant component according to claim 8 , wherein in atleast one of said first and second outer coating substrates, at leastone pair of capacitive electrodes are arranged to face each other andinterpose at least a portion of said first material layer, and acapacitor is defined by said pair of capacitive electrodes.
 14. Apiezoelectric resonant component according to claim 8 , wherein aresistive element and an inductance element are provided in at least oneof said first and second outer coating substrates and are made of aresistive material and a magnetic material, respectively.
 15. Apiezoelectric resonant component according to claim 8 , wherein at leastone of said first and second outer coating substrates has a plurality ofsaid first material layers.
 16. A piezoelectric resonant component,comprising: an outer coating substrate; a piezoelectric resonant elementdisposed on said outer coating substrate; and a cap disposed on saidouter coating substrate covering said piezoelectric resonant element;wherein said outer coating substrate includes a multilayered substratehaving a laminate structure defined by a first material layer and asecond material layer, the first material layer is capable of beingsintered in a liquid phase and the second material layer is not capableof being sintered at the sintering temperature of said first materiallayer.
 17. A piezoelectric resonant component according to claim 16 ,wherein said piezoelectric resonant element is an energy trappiezoelectric resonant element, and a space for allowing for free andunhindered vibration of said energy trap piezoelectric resonant elementis provided between said cap and said outer coating substrate.
 18. Apiezoelectric resonant component according to claim 17 , wherein aconcave portion is provided on a surface of said outer coatingsubstrate, and said space is defined by said concave portion.
 19. Apiezoelectric resonant component according to claim 16 , wherein saidfirst material layer is made of one of glass and glass-ceramics.
 20. Apiezoelectric resonant component according to claim 16 , wherein saidouter coating substrate does not contain a component that is capable ofdissolving into a wet plating bath.
 21. A piezoelectric resonantcomponent according to claim 16 , wherein at least one pair ofcapacitive electrodes are provided in said outer coating substrates andare arranged to face each other and interpose at least a portion of saidfirst material layer, and a capacitor is defined by said pair ofcapacitive electrodes.
 22. A piezoelectric resonant component accordingto claim 16 , wherein a resistive element and an inductance element areprovided in said outer coating substrate and are made of a resistivematerial and a magnetic material, respectively.
 23. A piezoelectricresonant component according to claim 16 , wherein said outer coatingsubstrate has a plurality of first material layers.
 24. A piezoelectricresonant component according to claim 16 , wherein a Young's modulus ofsaid outer coating substrate is less than a Young's modulus of apiezoelectric material constituting said piezoelectric resonant element.25. A piezoelectric resonant component according to claim 24 , whereinsaid outer coating substrate is a multilayered substrate having at leasttwo layers, and said multi-layered substrate has a first layer that hasa Young's modulus that is greater than the Young's modulus of thepiezoelectric material, and a second layer that has a Young's modulusthat is less than the Young's modulus of the piezoelectric material. 26.A piezoelectric resonant component according to claim 25 , wherein saidlayer having the smaller Young's modulus is made of a composite materialof amorphous glass and ceramic powder, and said layer having the greaterYoung's modulus is made of one of Al₂O₃ and MgTiO_(3.)
 27. Apiezoelectric resonant component according to claim 24 , wherein a capis disposed on said outer coating substrate and arranged to surroundsaid piezoelectric resonant element fixed on said outer coatingsubstrate.
 28. A piezoelectric resonant component according to claim 24, wherein said outer coating substrate has a concave portion to storesaid piezoelectric resonant element, and a cover member fixed to saidouter coating substrate is arranged to close said concave.